To obtain Instrument Flight Rules certification, a pilot must be trained to fly in Instrument Meteorological Conditions, with his or her vision occluded to the instrument panel of the airplane. Accordingly, a pilot must train for IFR certification by simulating IMC flying conditions. To achieve IMC simulation, a pilot can wear various training devices, such as hoods, visors, or glasses to block outside visual references. For the purposes of this discussion, the terms "IMC simulation" and "IFR training" will be used interchangeably. Existing IFR training devices are available which can restrict the pilot's field-of-view, but they are plagued with practical problems.
One existing IFR training device mounts to a pilot's headset. The headset-mounted device attaches to the flat metal stirrups found on some general aviation headsets. The headset-mounted device is constructed of a hard, opaque material and essentially surrounds the eyes of the pilot. The headset-mounted device has a forward viewing aperture which defines the wearer's field-of-view. Two pivoting arms allow the device to be manually raised and lowered. Although the device will accommodate some general aviation headsets, it cannot be worn with all types of headsets. Specifically, the device is limited to operation with selected aviation headsets from certain manufacturers.
Another problem with the headset-mounted device is that when engaged, the pilot cannot look down easily, which is often required in order to see navigational maps. The viewing aperture occludes the pilot's vision not only on the sides, but at the bottom of the device as well. Consequently, the pilot must either crane his neck downward, or use one hand to tilt the device upwards, neither solution being desirable. Repeatedly craning the neck downward increases the possibility that the pilot will suffer vertigo and become partially disoriented. Tilting the headset-mounted device upwards defeats the intended purpose of preventing outside visual references from being introduced.
A second existing IFR training device is a visor-type device. The visor-type device is typically either an attachable-hood style, or an integral visor-hood combination. The attachable-hood style device typically provides a hood that removably attaches to the bill of a visor or cap. The integral-hood style device is typically constructed such that the hood and the visor or cap are not detachable. Both styles share similar features. For both styles, the hood part has a forward portion, which extends forward from the bill of the visor or cap, and side portions, which extend downward from either side of the forward portion.
The visor-type device occludes the pilot's vision over the top of the instrument panel, but the design still allows excessive visual references in the pilot's peripheral vision. Moreover, the visor-type device occludes the pilot's vision equally on both the right and left sides. When the pilot sits in the cockpit of an IFR training-compatible airplane, the instrument panel is asymmetrically displaced about the pilot. In other words, when sitting in the left seat, there is more of the instrument panel to the right of the pilot than to the left. During IFR training, the pilot's field-of-view should include the entire instrument panel, but exclude all visual references above and to the sides of the instrument panel. Therefore, the pilot's field-of-view should be occluded asymmetrically to match the asymmetric displacement of the instrument panel about the pilot. In other words, when sitting in the left seat, the pilot should be able to see more to the right than to the left for a realistic IMC simulated environment, and vice versa.
Another IFR training device is a fogged-glasses device, which is visibly similar to protective glasses worn by a carpenter or craftsman. The pilot's viewing area is defined by an opaque or translucent treatment applied to the lenses of the goggles or glasses such that the wearer's vision is occluded to an instrument panel. These goggles, adapted for use as IFR training devices, suffer from several problems. First, wearing the device over regular glasses is very difficult and uncomfortable. The viewing area defined by the opaque treatment is symmetric, so the wearer's field-of-view is not skewed to one side. Moreover, the viewing area of the goggles allows excessive visual references to be introduced into the pilot's peripheral vision.
Additional problems with the glasses-type device are that many wearers complain that the device causes headaches from the pressure applied to the head by the earpieces, and the lenses often fog from perspiration during use. The lenses of the device are also susceptible to being scratched.
Yet another IFR training device is a mask-type device similar to a scuba diver's mask, held in place by an elastic headband. This mask-type device is constructed of an opaque, lightweight, shock-resistant plastic, and provides a small viewing aperture defining the pilot's field-of-view.
The mask-type device suffers from many of the same problems as the other existing devices. It is difficult to remove because the device is secured to the wearer's head with an elastic band that can become tangled with the pilot's headset and aviation goggles. Like the headset-mounted device, the mask-type device does not allow the pilot to look down easily. Also, because of the design, many pilots complain that the mask-type device is too snug and confining, almost creating a claustrophobic feeling while wearing it. Moreover, the pilot's field-of-view is not asymmetrically occluded.
Therefore, a practical IFR training device which can be comfortably worn over conventional aviation headsets and eyeglasses, which can constrict the pilot's field of view in an asymmetric manner, and which can adequately eliminate external references from the pilot's peripheral vision, has proven elusive to those skilled in the art. Accordingly, a need exists for an IFR training device that meets each of the above-described requirements.